Process for the manufacture of ground wood pulp



Patented July 14, 1931 UNITED STATES ALLISON R. CHAMBERS, OF NEW GLASGOW, NOVA SCOIIA, CANADA PROCESS FOR THE MANUFACTURE OF GROUND WOOD PULP Ho Drawing. Application flled'l'anuary 31, 1929, Serial No. 336,660, and in Canada January 16, 1929.

This invention relates to a process for the manufacture of ground wood pulp. The principal object of the invention is to so treat the pulp during the operation of grinding that it will produce longer, stronger and more uniform fibres, which fibres will be whiter and more easily bleached than fibres produced under present methods.

The invention consists essentially in utilizing salt (NaCl) or a salt solution, or brine, in any desired strength as a medium in which the pulp wood is ground; that is to say, instead of using water to cool the grindstones a salt solution, either sodium chloride, potassium chloride, or sodium silicate,.or other salts, or mixtures of salts, may be employed to cool the stone and float off the pulp as it is ground.

In carrying out my invention, I may uti lize common salt, which may be fed in suitable quantity into the grinding magazine at a convenient point near the surface of the grindstone, where it will be ground and dissolved as the fibres are being ground from the wood. The water in which the lower portion of the grindstone is immersed will, of course, become a salt solution and the strength of this salt solution may be regulated as desired by using the proper quantity of salt. Instead of using the salt crystals, I may use a salt solution sprayed or sprinkled onto the grinding surface during the operation of grinding the wood. Or the salt or brine solution in suitable strength may be fed to the grinding surface from the reservoir in which the lower portion of the stone is revolving. The amount of salt or salt solution usedmay be controlled so that the temperature of the pulp and stone during the grinding operation may be maintained at a suitable de ree. The pressure of the wood on the grin ing stone creates a heat zone with a comparatively high temperature and it is are being ground. The salt also cleans the stone as well as the fibres and prevents the accumulation of pitchy or resinous materials on the surface of the stone so that the opera-- tion of grinding the fibres is much more uniform. a

The salt or salt solution may be used in any strength :nd by controlling the amount of the salt to cool the stones, any suitable temperature may be maintained.

By grinding wood in the manner above described, I have found that an increased output may be expected and for use'in making newsprint and the like-a smaller percentage of sulphite may be employed than with pulp ground in the usual manner. Ground wood pulp made according to my process also has better keeping and storing properties than ordinary ground wood.

Having thus described my invention, what I 3. In the process of grinding Wood pulp,

hand.

ALLISON R. CHAMBERS. 

